Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
As far as possible he will deliver only what he has written, and, if circumstances permit, only what he has, as Demosthenes says, [*](This passage is our sole authority for the saying.) carved into shape. Such a practice is possible in first hearings and also in subsequent hearings such as are granted in the public courts after an interval of several days. On the other hand, when we have to reply on the spot, it is impossible to prepare everything: in fact for the less ready type of speaker, it may, in the event of his opponents putting forward arguments quite other than those which they were expected to advance, be a positive drawback to have